SignatureDoesNotMatch using Aws::S3::Object#presigned_url

[doooby]

Hello, I am trying to do a very simple direct to S3 upload funcionality, but cannot get over 403 Forbidden response.

@new_s3_object = Aws::S3::Object.new S3_BUCKET.name, 'test22.jpg', client: S3_BUCKET.client
url = @new_s3_object.presigned_url :put, acl: 'public-read'

That url I hand over to jquery's fileupload and it fails returning 403 with this xml:

<Error>
<Code>SignatureDoesNotMatch</Code>
<Message>The request signature we calculated does not match the signature you provided. Check your key and signing method.</Message>
<AWSAccessKeyId> ... </AWSAccessKeyId>
<StringToSign>AWS4-HMAC-SHA256 20141221T170842Z 20141221/eu-central-1/s3/aws4_request 541ba474d07a24d8a423a77292f45ef245246cf6c4bcf2bdb95366181a049509</StringToSign>
<SignatureProvided>4df9b85ee41319719dbe4a470df9f485a642521096b47298e4541ac8c9da7819</SignatureProvided>
<StringToSignBytes> ... </StringToSignBytes>
<CanonicalRequest>POST /test22.jpg X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Credential= ... %2F20141221%2Feu-central-1%2Fs3%2Faws4_request&amp;X-Amz-Date=20141221T170842Z&amp;X-Amz-Expires=900&amp;X-Amz-SignedHeaders=host&amp;x-amz-acl=public-read host:my-bucket.s3.eu-central-1.amazonaws.com host UNSIGNED-PAYLOAD</CanonicalRequest>
<CanonicalRequestBytes> .. </CanonicalRequestBytes>
<RequestId>9F8E4357C44EA940</RequestId>
<HostId>HyUCoqgs9vfqzU+Oy+PR112JOrYCnxaLpBcm0hqCffpm60adFoOrM2g5EpcQe1L22EFjhef34iw=</HostId>
</Error>

The thing is, that this code on server-side goes successfuly (and the file appears in the bucket):

@new_s3_object.upload_file '/path-to-anythwhere/test22.jpg', acl: 'public-read'

That's why I am sure, that everything should be set up just right. As far I've had the patience to dig into this library, I've concluded that both #upload_file and #presigned_url are using same internals for generating requisite headers/parametrs So could you point me to what's wrong?

[kabaka]

You are calling presigned_url with request type :put and then performing an HTTP POST request:

<CanonicalRequest>POST /test22.jpg X-Amz-Algorithm=AWS4-HMAC-SHA256&amp;X-Amz-Credential= ... %2F20141221%2Feu-central-1%2Fs3%2Faws4_request&amp;X-Amz-Date=20141221T170842Z&amp;X-Amz-Expires=900&amp;X-Amz-SignedHeaders=host&amp;x-amz-acl=public-read host:my-bucket.s3.eu-central-1.amazonaws.com host UNSIGNED-PAYLOAD</CanonicalRequest>

My understanding is that there is currently no support for generating a pre-signed POST URL. See #173.

[trevorrowe]

@kabaka You are correct. I am not opposed to adding a pre-signed POST helper, but I would want to see it built around signature version 4. The v1 Ruby SDK uses the v2 S3 signature and will not work in any of the newest regions.

[doooby]

I'll leave here this gist I've made https://gist.github.com/doooby/2cb24eb2ea1180755c3c . It's my implementaion of simultaneous multiple images browser-based uploading to S3 using POST request with signature v4. It's build on top of this gem (aws-sdk v2.0.16.pre) and Rails. Maybe you could embed the DirectPostHelper class or at least use its code to add this feature.